SIADH antidiuretic hormone

Syndrome of inappropriate antidiuretic hormone is defined by water retention, dilutional hyponatraemia and decreased volume of highly concentrated urine. There are several causes which can result in SIADH, neoplasms ectopic secreting AVP, ectopic release of AVP by various diseases or drugs, exogenous administration of AVP, desmopressin, lysipressin or large doses of OT (iatrogenic SLADH). 

SIADH Syndrome of inappropriate antidiuretic hormone TID Three times daily (ter in die)... 

The potent antidiuretic hormone AVP orchestrates the regulation of free water absorption, body fluid osmolality, cell contraction, blood volume, and blood pressure through stimulation of three G-protein-coupled receptor subtypes Vi-vascular types a and b, V2-renal, and V3-pituitary. Increased AVP secretion is the trademark of several pathophysiological disorders, including heart failure, impaired renal function, liver cirrhosis, and SIADH. As a consequence, these patients experience excess water retention or inadequate free-water excretion, which results in the dilution of sodium concentrations, frequently manifesting as clinical hyponatremia (serum sodium concentration <135mmol/L). This electrolyte imbalance increases mortality rates by 60-fold. Selective antagonism of the AVP V2 receptor promotes water... 

Causes of nonosmotic release of arginine vasopressin, commonly known as antidiuretic hormone, include hypovolemia decreased effective circulating volume as seen in patients with congestive heart failure nephrosis cirrhosis and syndrome of inappropriate antidiuretic hormone (SIADH) release. 

FIGURE 78-1. Diagnostic algorithm for the evaluation of hyponatremia. (CHF, congestive heart failure EABV, effective arterial blood volume SIADH, syndrome of inappropriate antidiuretic hormone UNa, urine sodium concentration Uosm, urine osmolality.)... 

Loss of blood glucose control When a patient stabilized on any diabetic regimen is exposed to stress such as fever, trauma, infection, or surgery, a loss of control may occur. At such times, it may be necessary to discontinue the drug and give insulin. Disulfiram-like syncframe. A sulfonylurea-induced facial flushing or breathlessness reaction may occur when some sulfonylureas are administered with alcohol. Syndrome of inappropriate secretion of antidiuretic hormone (SIADH) Water retention and dilutional hyponatremia have occurred after administration of sulfonylureas to type 2 diabetes patients, especially those with CHF or hepatic cirrhosis. 

Hyponatremia Hyponatremia and the syndrome of inappropriate antidiuretic hormone secretion (SIADH) may occur with venlafaxine. 

Nephrogenic diabetes insipidus is due to resistance to action of vasopressin, and therefore DDAVP is not indicated, but some benefit may be gained by using thiazide diuretics or chlorpropamide. The syndrome of inappropriate antidiuretic hormone (SIADH) can be treated by using the antibiotic derivative demeclocycline to induce a state of vasopressin resistance and partial nephrogenic diabetes insipidus. 

Bouman WP Pinner G, lohnson H. Incidence of selective serotonin reuptake inhibitor (SSRI) induced hyponatraemia due to the syndrome of inappropriate antidiuretic hormone (SIADH) secretion in the elderly. Int 1 Geriatr Psychiatry 1998,13 12-15. 

Abbreviations CNS, central nervous system COX, cyclooxygenase Gl, gastrointestinal NSAlDs, nonsteroidal anti-inflammatory drugs SIADH, syndrome of inappropriate antidiuretic hormone secretion. From Pick DM, Cooper IW, Wade WE, et al Updating the Beers criteria for potentially inappropriate medication use in older adults Results of a U.S. consensus panel of experts. Arch Intern Med 2003 163 2716. 

BUN, blood urea nitrogen CBC, complete blood cell count CBZ, carbamazepine DVP, divalproex sodium EKG, electrocardiogram SIADH, syndrome of inappropriate secretion of antidiuretic hormone TSH, thyroid-stimulating hormone. 

Note. SIADH=syndrome of inappropriate secretion of antidiuretic hormone CBC=complete blood count TSH=thyroid-stimulating hormone ECG=electrocardiogram AST=aspartate aminotransaminase ALT=alanine aminolransaminase. 

The syndrome of inappropriate antidiuretic hormone (SIADH) secretion is a condition in which secretion of ADH continues despite serum hypo-osmolarity. This results in fluid retention and hyponatremia that can lead to brain oedema, mental confusion and coma. The causes are hypothalamic-pituitary tumours or an ectopic vasopressin-secreting tumour. 

Antidiuretic hormone antagonists are used to manage SIADH when water restriction has failed to correct the abnormality. This generally occurs in the outpatient setting, where water restriction cannot be enforced, or in the hospital when large quantities of intravenous fluid are needed for other purposes. Lithium carbonate has been used to treat this syndrome, but the response is unpredictable. Demeclocycline, in dosages of 600-1200 mg/d, yields a more predictable result and is less toxic. Appropriate plasma levels (2 mcg/mL) should be maintained by monitoring. Unlike demeclocycline, conivaptan is administered by IV injection, so it is not suitable for chronic use in outpatients. Lixivaptan and tolvaptan should soon be available for oral use. 

Antidiuretic hormone is also elevated in response to diminished effective circulating blood volume, as often occurs in congestive heart failure. When treatment by volume replacement is not desirable, hyponatremia may result. As for SIADH, water restriction is often the treatment of choice. In patients with congestive heart failure, this approach is often unsuccessful in view of increased thirst and the large number of oral medications being used. In these patients, conivaptan may be particularly useful because it has been found that... 

The main dose-limiting toxicity is neurotoxicity, usually expressed as a peripheral sensory neuropathy, although autonomic nervous system dysfunction with orthostatic hypotension, urinary retention, paralytic ileus, or constipation, cranial nerve palsies, ataxia, seizures, and coma have been observed. While myelosuppression occurs, it is generally milder and much less significant than with vinblastine. The other potential adverse effect that can develop is the syndrome of inappropriate secretion of antidiuretic hormone (SIADH). 

In an unusual case reported in detail from Saudi Arabia, a 28-year-old woman receiving gonadotropins developed acute respiratory distress, abdominal pain, and severe hyponatremia associated with the syndrome of inappropriate antidiuretic hormone secretion (SIADH) (19). A multiple pregnancy nevertheless resulted and three fetuses went to term successfully. 

Furosemide rarely causes the syndrome of inappropriate antidiuretic hormone secretion (SIADH) (although it has been found useful in treating some patients with SIADH who cannot tolerate water restriction (428)). In furosemide-induced cases (SEDA-7, 246), serum ADH concentrations were raised, total body sodium was normal, total body potassium greatly reduced, and intracellular water raised at the expense of extracellular fluid volume. However, such cases are rare, and no new cases have been published since this complication was reported in SEDA-7. 

There has been a single case report of inappropriate secretion of antidiuretic hormone (SIADH) attributed to mizoribine (725). 

A 74-year-old man with rheumatoid arthritis developed nausea and headache 1.5 months after starting to take mizoribine. His serum sodium concentration fell to 118 mmol/1, but his urinary sodium excretion was normal and there was no hypotension or hemoconcentration. His serum antidiuretic hormone concentration was raised at 0.59 pg/ml in spite of a reduced serum osmolality to 254 mosm/kg. He had no organic disease likely to cause SIADH. Despite infusion of hypertonic saline, his serum sodium concentration did not return to normal. Shortly after mizoribine withdrawal, his serum sodium increased... 

The syndrome of inappropriate secretion of antidiuretic hormone (SIADH) (728) may be the mechanism of action underlying cases of peripheral edema that have been described (SEDA-2, 12 SEDA-6, 28). Diuretics are not helpful, but dosage reduction produces relief (729). 

A rare but well-known adverse effect of vinca alkaloids, including vinorelbine, is the syndrome of inappropriate secretion of antidiuretic hormone (SIADH) (1195-1197). The diagnosis is usually based on clinical and laboratory... 

Ikegami H, Shiga T, Tsushima T, Nirei T, Kasanuki H. Syndrome of inappropriate antidiuretic hormone secretion (SIADH) induced by amiodarone a report on two cases. J Cardiovasc Pharmacol Ther 2002 7(l) 25-8. 

Castrillon JL, Mediavilla A, Mendez MA, Cavada E, Carrascosa M, Valle R. Syndrome of inappropriate antidiuretic hormone secretion (SIADH) and enalapril. J Intern Med 1993 233(1) 89-91. 

Hyponatremia is caused by an excess of total body water relative to total body sodium and can result from a number of underlying conditions, including the syndrome of inappropriate antidiuretic hormone secretion (SIADH), cirrhosis, and congestive heart failure (CHF). In each of these conditions, inappropriate production of arginine vasopressin (AVP) [also known as vasopressin or antidiuretic hormone (ADH)], a neurohormone that regulates renal electrolyte-free water reabsorption, contributes to enhanced renal water retention, leading to decreased serum sodium concentrations.7 Hyponatremia can be characterized as hypervolemic, euvolemic, or hypovolemic... 

The syndrome of inappropriate secretion of antidiuretic hormone (SIADH) is a possible adverse effect of the SSRIs (SEDA-14, 14) (SEDA-18, 20) (SEDA 21, 11) (40). The mechanism is not known. Several of the affected patients have been elderly, and old people may be at greater risk. 

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